import React, { Component } from 'react'

export default class Counter extends Component {
    render() {
        return (
            <div style={{ marginLeft: '30px' }}>
                <h1>当前求和为：{this.props.count}</h1>
                <select ref={c => this.selectNumber = c}>
                    <option value="1">1</option>
                    <option value="2">2</option>
                    <option value="3">3</option>
                </select>&nbsp;
                <button onClick={this.increment}>+</button>&nbsp;
                <button onClick={this.decrement}>-</button>&nbsp;
                <button onClick={this.incrementIfOdd}>odd +</button>&nbsp;
                <button onClick={this.incrementAsync}>asnyc +</button>&nbsp;
            </div>
        )
    }
    increment = () => {
        const { value } = this.selectNumber
        this.props.increment(value * 1)
    }
    decrement = () => {
        const { value } = this.selectNumber
        this.props.decrement(value * 1)
    }
    incrementIfOdd = () => {
        const { value } = this.selectNumber
        if (this.props.count % 2 === 0) {
            return
        }
        this.props.increment(value * 1)
    }
    incrementAsync = () => {
        const { value } = this.selectNumber
        this.props.incrementAsync(value * 1,500)
    }
}
